摘要
返回有效变换方法列表。 对于某个特定的地理区域，可以使用区域范围来缩小有效变换方法列表的范围。
最合适的变换通常是返回列表中的第一个。 该列表按数据与变换使用区域的重叠数量进行排序。 如果两个或多个变换与数据的重叠数量相同，则变换精度值将用作辅助排序参数。
语法
ListTransformations (from_sr, to_sr, {extent}, {vertical}, {first_only})| 参数 | 说明 | 数据类型 |
from_sr | The starting geographic coordinate system. This can be specified with a SpatialReference object, the name of the spatial reference, or a path to a projection file (.prj). | SpatialReference |
to_sr | The final geographic coordinate system. This can be specified with a SpatialReference object, the name of the spatial reference, or a path to a projection file (.prj). | SpatialReference |
extent | Only transformations that span the entire extent will be returned. The extent needs to be specified in coordinates from the from_sr. When working with data, the extent on a Describe object can be used. | Extent |
vertical | Specifies whether to return a list of vertical or horizontal transformations. By default, the function returns transformations that ignore vertical coordinate systems on the from_sr and to_sr. The function returns only one type of transformation. If set to False, horizontal transformations will be returned; if set to True, vertical transformations will be returned. To use True, both the from_sr and to_sr arguments must have a vertical coordinate system. To use a transformation result as input to the Project tool, the tool's vertical parameter must be set appropriately to NO_VERTICAL or VERTICAL to match the transformation. (默认值为 False) | Boolean |
first_only | Specifies whether to limit the list of transformations to a single item or return all valid transformations. This is a performance optimization. (默认值为 False) | Boolean |
| 数据类型 | 说明 |
| String | 有效变换方法列表。 |
代码示例
使用 ListTransformations 函数确定可用于从一个坐标系投影到另一个坐标系的有效变换。
import arcpy
from_sr = arcpy.SpatialReference('WGS 1984')
to_sr = arcpy.SpatialReference('NAD 1927 StatePlane California VI FIPS 0406')
extent = arcpy.Extent(-178.217598182, 18.9217863640001,
-66.969270909, 71.4062354550001)
transformations = arcpy.ListTransformations(from_sr, to_sr, extent)